Special Counsel Robert Mueller’s inquiry into alleged Russian interference in the 2016 election is ongoing.

So far, four Americans – Michael Flynn, Paul Manafort, Richard Gates and George Papadopoulos – have been charged, though none of the charges are directly related to any misconduct by President Trump’s campaign. Additionally, more than a dozen Russian nationals have been indicted.

The special counsel filed new tax evasion and bank fraud charges against Manafort and Gates this week, potentially increasing the amount of prison time the pair could face if convicted at trial. The charges are similar to those filed in October.

Here’s a breakdown of the charges, and a closer look at those who have faced charges throughout Mueller’s nearly year-long probe.

Michael Flynn

Flynn reportedly lied about his talks with Russia’s ambassador to Washington. In late 2016, while former President Barack Obama was still in office, the two allegedly spoke about the U.S. sanctions imposed on Russia.

This raised concerns that Flynn, a retired Army lieutenant general, misled Trump officials about his conversations with Russian officials.

Paul Manafort

Paul Manafort turned himself in to authorities in October.

(The Associated Press)

The special counsel filed a 32-count indictment on Feb. 22 against former Trump campaign chairman Paul Manafort and aide Rick Gates, accusing the pair of tax evasion and bank fraud.

The new indictment accuses Manafort and Gates of doctoring documents to inflate the income of their businesses and then using those fraudulent documents to obtain loans. It also accuses Manafort of evading taxes from 2010 through 2014 and in some of the years concealing his foreign bank accounts.

Manafort turned himself in to federal authorities in the fall. The 68-year-old served as Trump’s campaign manager for a few months in 2016. Gates, Manafort’s business associate, also turned himself in at the time.

Manafort was initially charged in a 12-count indictment in connection with foreign lobbying work, and he pleaded not guilty. The charges included: conspiracy against the U.S., conspiracy to launder money, false statements, unregistered agent of a foreign principal, and multiple counts of failure to file reports of foreign bank and financial accounts, according to a special counsel’s office spokesman.

Manafort sued to have the case against him dismissed and argued that Mueller had overstepped his bounds by charging him for conduct he says is unrelated to Russian interference in the 2016 election.

Richard Gates

Richard Gates pleaded not guilty to all charges.

(The Associated Press)

Gates was named alongside Manafort in the recent charges brought by the special counsel. He’s accused of 11 counts related to filing false income tax returns and three counts of failure to report foreign bank and financial accounts.

Like Manafort, Gates was indicted in October in connection with foreign lobbying work and pleaded not guilty. His charges are similar to Manafort’s, ranging from conspiracy against the U.S. to conspiracy to launder money.

George Papadopoulos

George Papadopoulos pleaded guilty to the charges against him.

(Alexandria Sheriff’s Office)

A former foreign policy adviser to Trump’s presidential campaign, George Papadopoulos pleaded guilty in 2017 to making false statements to the FBI regarding “the timing, extent and nature of his relationships and interactions with certain foreign nationals whom he understood to have close connections with senior Russian government officials,” according to court documents.

He also reportedly tried to set up meetings between Russian and Trump campaign officials on various occasions.

Alex van der Zwaan

Attorney Alex van der Zwaan pleaded guilty to lying to investigators about his interactions with Gates.

(Reuters/Yuri Gripas)

Mueller’s team charged Alex van der Zwaan, an attorney who allegedly lied to federal investigators in the Russia probe, in federal court on Feb. 16. He pleaded guilty days later.

According to charging documents, van der Zwaan was employed by a law firm hired by the Ukraine Ministry of Justice in 2012. He admitted to lying about his interactions with Gates.

The charge against van der Zwaan does not involve election meddling or the Trump campaign’s operations. It stems from the special counsel’s investigation into a covert Washington lobbying campaign Manafort and Gates are accused of directing on behalf of pro-Russian Ukrainian interests.

The law firm where he used to work says it fired him last year and has been cooperating with authorities.